Left/Right - Good when editing, Bad on output

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Left/Right - Good when editing, Bad on output

Permanent link to this post Posted by twitchmatic » Mon Oct 30, 2017 5:57 pm

MacOS Sierra - 10.12.6
Audacity - 2.0.5

I am currently working on a project that has specific sounds on the left/right channel. When I'm working on the aup project file and playback, it pans left/right correctly when it is supposed to.

However, when I export (have tried several different formats), the sounds that should be in the left channel only, also come across in the right channel. Not sure where to start troubleshooting this?

Thanks!
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Re: Left/Right - Good when editing, Bad on output

Permanent link to this post Posted by steve » Mon Oct 30, 2017 6:11 pm

Try importing the file that you exported, back into Audacity. If it plays OK in Audacity, then the problem is with the playback system. If it does not play correctly in Audacity (but the original project does), then the problem is with the exported file.
9/10 questions are answered in the FREQUENTLY ASKED QUESTIONS (FAQ)
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Re: Left/Right - Good when editing, Bad on output

Permanent link to this post Posted by Trebor » Mon Oct 30, 2017 7:58 pm

twitchmatic wrote:However, when I export (have tried several different formats), the sounds that should be in the left channel only, also come across in the right channel. Not sure where to start troubleshooting this?

Some computer sound-cards apply a "virtual surround-sound" effect : that mixes the left & right channels a little, (aka crossover). If that is the cause, the "virtual surround-sound" can be turned-off, (but I don't know where that is on a Mac).
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Re: Left/Right - Good when editing, Bad on output

Permanent link to this post Posted by twitchmatic » Mon Oct 30, 2017 11:15 pm

Ok, after much more troubleshooting, here are some updates: 1
1) The audio from the track seeps through to the right track, both in the aup file and output. It's more pronounced in the output which is why I couldn't at first notice it on the aup file.
2) I have tested multiple outputs (mp3, ac3) and also tested multiple speakers / players to ensure it's not my mac (iphone, mac speakers, mac via headphone jack).

Here is an image https://imgur.com/a/LAznC where, to troubleshoot, Track one is Left and pan is set to left. Track to is right and panned to right. During the visible spot here, there should only be audio on the left channel. Right now, there is audio on the left channel And audio (although super quiet) on the right channel. It's super-quiet (but definitely there) in the aup file and much louder when I export it.

I hope this is making sense because it's driving me nuts :)
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Re: Left/Right - Good when editing, Bad on output

Permanent link to this post Posted by kozikowski » Tue Oct 31, 2017 2:08 am

Drag-select a portion of the "dead" track and Analyze > Contrast > Measure Selection. When I do that, I get background noise in the -85dB range. Practically zero. That's what you should get. I expect it to work.

Macs don't naturally apply effects and filters to playback in real time, but an application could be "helping you."

This is a Left-Right sound test I shot a while ago. It's 39 seconds.

http://www.kozco.com/tech/LRMonoPhase4.wav

It's clean.

Koz
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Re: Left/Right - Good when editing, Bad on output

Permanent link to this post Posted by kozikowski » Tue Oct 31, 2017 2:22 am

When you push the sliders to the left and right extremes, does the little action graphic say "100%?"

The two export file types you gave as illustration are both compressed filetypes and "mess with the sound." Does it do that if you Export WAV (Microsoft).

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Re: Left/Right - Good when editing, Bad on output

Permanent link to this post Posted by twitchmatic » Tue Oct 31, 2017 2:45 am

Fascinating! This is super-helpful - thank-you!

- The pan left/right is at 100%
- It occurs with a WAV file as well
- It does it to the sample you provided as well (on my mac, played either via VLC or Audacity) - I.E. I hear your voice (at a much less volume level) in my right ear when you are speaking on the left and vice versa.
- It does a similar thing while playing it on my iPhone with Quicktime (i.e. nothing to do with my computer)

However, it does NOT do it (the sound is 100% clean) when I airplay it to my amp/speakers. That is very bizarre.

Thank-you for the sample - help me to realize it wasn't me. I have spent hours on this project trying to figure this out :)
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Re: Left/Right - Good when editing, Bad on output

Permanent link to this post Posted by kozikowski » Tue Oct 31, 2017 3:18 am

help me to realize it wasn't me.

That's why I recorded that piece. Basic troubleshooting. Split the system in half and see which half breaks.

The original reason for that test clip was to test for accidental wires reversed in sound systems. The fourth segment, "out of phase" should sound odd or like it's coming from behind you. If the wrong segment does that, you got problems. The fourth segment should vanish in mono-mix systems.

Etc.

Are all the errors happening with one set of earphones? Beats by Dr Dru, or Dr Dre. One of those doctors.

Do you still have the earbuds you got with your iPhone/iPod?

Koz
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Re: Left/Right - Good when editing, Bad on output

Permanent link to this post Posted by kozikowski » Tue Oct 31, 2017 3:20 am

OK, probably not that one.

http://drdrew.com/about-dr-drew/

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Re: Left/Right - Good when editing, Bad on output

Permanent link to this post Posted by twitchmatic » Tue Oct 31, 2017 3:28 am

Are all the errors happening with one set of earphones? Beats by Dr Dru, or Dr Dre. One of those doctors.

Do you still have the earbuds you got with your iPhone/iPod?


it was three different headphones I used (all with the same result). I will see if I can track down the original Apple ones.... Thanks again for all of your help.
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